-use rustc::lint::*;
-use rustc::ty::TypeVariants;
use rustc::hir::*;
+use rustc::lint::*;
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
+use rustc::ty::{self, Ty};
use syntax::codemap::Span;
-use utils::{higher, snippet, span_lint_and_then};
+use crate::utils::{higher, is_copy, snippet, span_lint_and_sugg};
+use crate::consts::constant;
-/// **What it does:** This lint warns about using `&vec![..]` when using `&[..]` would be possible.
+/// **What it does:** Checks for usage of `&vec![..]` when using `&[..]` would
+/// be possible.
///
/// **Why is this bad?** This is less efficient.
///
/// ```rust,ignore
/// foo(&vec![1, 2])
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub USELESS_VEC,
- Warn,
+ perf,
"useless `vec!`"
}
}
}
-impl LateLintPass for Pass {
- fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
// search for `&vec![_]` expressions where the adjusted type is `&[_]`
- if_let_chain!{[
- let TypeVariants::TyRef(_, ref ty) = cx.tcx.expr_ty_adjusted(expr).sty,
- let TypeVariants::TySlice(..) = ty.ty.sty,
- let ExprAddrOf(_, ref addressee) = expr.node,
- ], {
- check_vec_macro(cx, addressee, expr.span);
- }}
+ if_chain! {
+ if let ty::TyRef(_, ty, _) = cx.tables.expr_ty_adjusted(expr).sty;
+ if let ty::TySlice(..) = ty.sty;
+ if let ExprKind::AddrOf(_, ref addressee) = expr.node;
+ if let Some(vec_args) = higher::vec_macro(cx, addressee);
+ then {
+ check_vec_macro(cx, &vec_args, expr.span);
+ }
+ }
// search for `for _ in vec![…]`
- if let Some((_, arg, _)) = higher::for_loop(expr) {
- // report the error around the `vec!` not inside `<std macros>:`
- let span = cx.sess().codemap().source_callsite(arg.span);
- check_vec_macro(cx, arg, span);
+ if_chain! {
+ if let Some((_, arg, _)) = higher::for_loop(expr);
+ if let Some(vec_args) = higher::vec_macro(cx, arg);
+ if is_copy(cx, vec_type(cx.tables.expr_ty_adjusted(arg)));
+ then {
+ // report the error around the `vec!` not inside `<std macros>:`
+ let span = arg.span
+ .ctxt()
+ .outer()
+ .expn_info()
+ .map(|info| info.call_site)
+ .expect("unable to get call_site");
+ check_vec_macro(cx, &vec_args, span);
+ }
}
}
}
-fn check_vec_macro(cx: &LateContext, vec: &Expr, span: Span) {
- if let Some(vec_args) = higher::vec_macro(cx, vec) {
- let snippet = match vec_args {
- higher::VecArgs::Repeat(elem, len) => {
- format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len")).into()
+fn check_vec_macro<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, vec_args: &higher::VecArgs<'tcx>, span: Span) {
+ let snippet = match *vec_args {
+ higher::VecArgs::Repeat(elem, len) => {
+ if constant(cx, cx.tables, len).is_some() {
+ format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len"))
+ } else {
+ return;
}
- higher::VecArgs::Vec(args) => {
- if let Some(last) = args.iter().last() {
- let span = Span {
- lo: args[0].span.lo,
- hi: last.span.hi,
- expn_id: args[0].span.expn_id,
- };
+ },
+ higher::VecArgs::Vec(args) => if let Some(last) = args.iter().last() {
+ let span = args[0].span.to(last.span);
- format!("&[{}]", snippet(cx, span, "..")).into()
- } else {
- "&[]".into()
- }
- }
- };
+ format!("&[{}]", snippet(cx, span, ".."))
+ } else {
+ "&[]".into()
+ },
+ };
- span_lint_and_then(cx, USELESS_VEC, span, "useless use of `vec!`", |db| {
- db.span_suggestion(span, "you can use a slice directly", snippet);
- });
- }
+ span_lint_and_sugg(
+ cx,
+ USELESS_VEC,
+ span,
+ "useless use of `vec!`",
+ "you can use a slice directly",
+ snippet,
+ );
}
+/// Return the item type of the vector (ie. the `T` in `Vec<T>`).
+fn vec_type(ty: Ty) -> Ty {
+ if let ty::TyAdt(_, substs) = ty.sty {
+ substs.type_at(0)
+ } else {
+ panic!("The type of `vec!` is a not a struct?");
+ }
+}